[Ham-Mac] Re: Backup

[David Ferrington]

On the issue of another HD failing - yes that¹s likely to happen at some
point - most HD's fail at some time in there life (in the past, I would
reckon on one failure/year for every 1000 disks) - depending upon
environment, manufacture, usage, misuse etc.

The point is there is a very, very small chance of both disks failing at
once - there is a much greater risk of something happening to the disk
environment, like a fire or theft.

A number of big corporations (including the Bank I currently consult at) use
a very large array of HD to simulate offline, offsite, tape storage (in this
case made by a company called NetApp) - it's still a HD, but it's at a site
25km away from main server farm.
And the important data (i.e. for Banking compliance, 7yrs worth etc.) gets
transferred to tape from there and that goes to a different secure storage
location.


Forgive the length of the mail, and perhaps my humble opinions, but if you
want something to think about around backup and why/how I do it, read on :-)

As I see it, there are at least the following reasons for backing up:

+ to project against a HD failure
- backup to another HD, if the data is very dynamic and its business
  critical, use RAID
= I use 2 HD's, one is removable and gets rotated every week, so I have two
  weeks worth, the other is a LaCie 500GB d2 (just purchased to replace
  smaller HD, I've run out of space) - this reduces the risk of failure to
  a figure smaller than that of me getting to be a Space Station Ham :-)
  This does my MLDX log etc, basically my Documents/Library/Readerware db
  etc. and the current years (2006) iPhotos.


+ to protect against corruption (stupid human error, like deleting the wrong
  file or making a bad change, also to protect against stupid s/w error like
  Excel corrupting one of my spreadsheets)
- the method above does this to a reasonable degree, although I'm looking
  for something that will do incremental backup every 15 mins
= looks like I may need to write some Perl to do this with rsync


+ to protect against fire and theft
- backup to some form of removable media and take it offsite,
  CD/DVD/TAPE etc - I don't like removable HD for this, its too vulnerable
  and if its the 'dock-a-disk' type, you may not be able to find a dock in
  future
= 5 years worth of previous years iPhoto (2000-2004) are on DVD and I make 2
  copies, one goes to a family member 120km away (ok, even 1 km away would
  have been ok, but they are in IT too and we swap backups), the other stays
  with me. I'm using DVD ROM for 2005 to 2009 (burning once a year) and
  again make 2 copies. Ok, the cost of writable DVDs is small - I might
  consider just writing one copy a year, although its more to store, but
  less risk.
  Everything also goes to VXA tape every now and then via Retrospect (I
  should do it much more regularly, but it does take 2 days and 3 80GB tapes
  @ £70 each). I keep the current set and the previous goes offsite (that
  includes the iTunes library).
  Up till now I have not backed up my iTunes every day, because I've been
  ripping off my collection and not downloading from the web and I reasoned
  I had the CD's or could re-buy - however, that¹s changed - having had an
  irreplaceable CD stolen along with a car (yes thank god I had ripped
  it off) and now I've started downloading, so will burn smart playlist of
  downloaded music (I set the comment to indicate it), just to avoid expense
  of getting it again etc.

+ to provide regulatory authority history
- i.e. 7 years worth of accounts etc
= I burn CDs (because not everyone can read DVD) with a years worth of
  finalised accounts on each

Well, that¹s about it, if anyone can think of more reasons, other methods
etc, I'd be pleased to hear it.

-- 
Extraordinary claims require extraordinary evidence.
-Carl Sagan, astronomer and author (1934-1996)